Studies of the chromosome architecture of clones of the parthenogenetic grasshopper Warramaba virgo will be continued and extended, using a C-banding technique for the identification of new clones. Homogenized tissues will be sent to Professor Guy Bush (University of Texas) in liquid nitrogen for allozyme studies. Professor W.R. Atchley (University of Wisconsin) will carry out biometrical studies. Material will be sent in liquid nitrogen to Dr. John Avise (University of Georgia) for study of mitochondrial DNAs. C-banding studies will be extended to include related bisexual species of the genus Warramaba. A number of interracial and interspecific crosses will be set up between members of the grasshopper genus Vandiemenella differing in respect of chromosomal rearrangements. Detailed cytogenetic studies will be carried out on the hybrids, using C-banding and autoradiography on embryonic mitosis and on male meiosis. Preliminary work by a graduate student on the grasshopper species Keyacris scurra has demonstrated a polymorphism for C-banding pattern in the X-chromosome, but there is an apparent absence of females heterozygous for band pattern in the natural populations. In 1980 laboratory crosses will be carried out to investigate the cause of this absence, which may involve suppression of the expression of a band in the heterozygotes.